bio ms notes

• Some athletes train at high altitude.

  Training at high altitude increases the number of red blood cells per cm3 of blood.

  Explain why having more red blood cells per cm3 of blood is an advantage to an athlete.

  more haemoglobin so more oxygen can be carried so more energy released for muscles.
• Explain why the masses of the eggs increased.

  water entered by osmosis from dilute solution in beaker to more concentrated solution in egg through partially permeable membrane
• Explain how the student could modify the investigation to determine the concentration of the solution inside each egg.

  use five different concentrations of sugar solutions.plot percentage change on a graph to determine the concentration where the curve crosses the zero percentage change
• Explain how calcium ions are moved from the shell into the cytoplasm of the egg.

  ions move from an area of low concentration to high concentration

  by active transport which requires using energy
• A farmer thinks a potato crop is infected with potato virus Y (PVY).

  The farmer obtains a monoclonal antibody test kit for PVY.

  To make the monoclonal antibodies a scientist first isolates the PVY protein from the virus.

  Describe how the scientist would use the protein to produce the PVY

  monoclonal antibody.

  inject the protein into a mouse.combine lymphocytes with

  tumour cells to make hybridoma cells.find a hybridoma which makes a

  monoclonal antibody specific to PVY. clone the hybridoma to produce many cells to make the antibody
• Lung transplants from donors have risks. One risk is organ rejection.

  Scientists are researching how to solve the problem of organ rejection and hope to use stem cells to create healthy lungs.

  The healthy lungs can then be transplanted into CF patients without the risk of organ rejection.

  Describe how scientists may use stem cells to create healthy lungs that are not rejected by the CF patient.


  take stem cells from patient .remove CF gene. create embryo using these stem cells remove stem cells from embryo and allow them to differentiate into lung cells
• Explain the difference in the results for the two test tubes in Table 9.

  bile emulsifies fats creates a larger surface area so lipase can break down fat to produce fatty acids more quickly
• Describe the transport of water through a plant from the roots to the atmosphere.

  transported in xylem via transpiration.water evaporates (from leaves).through the stomata
• Evaluate the use of mechanical replacement heart valves and biological replacement heart valves.

  mechanical valves- longer lasting.less likely to need replacing.blood clots are more likely so patient has to take anti-clotting medication (for the rest of their lives). if medication not taken, clots can lead to heart attack. medication can lead to excessive bleeding after an injury. biological valves- no additional medication required. valve may harden.

  more likely to be rejected.ethical issue surrounding animals.

  • both are readily available

  • little wait time
• The body cells of a person with untreated diabetes lose more water than the body cells of a person who does not have diabetes.

  Explain how diabetes can cause the body cells to lose more water.

  the blood is more concentrated than cells so water moves out of cells by osmosis through a partially permeable membrane
• Glucose is absorbed into the blood in the small intestine by both diffusion and active transport.

  Describe how the small intestine is adapted for efficient absorption.

  villi provide a large surface area.walls of villi are one cell thick for shorter diffusion distance.good blood supply to maintain concentration gradient.cells have many mitochondria for respiration for active transport.
• One symptom of pancreatic cancer is weight loss.Explain how pancreatic cancer may cause a person to lose weight. Do not refer to hormones in your answer.

  reduced enzyme production release.food is not broken down.less glucose absorbed into the bloodstream so less glucose available for

  respiration so more fat used up in respiration/metabolism.
• Scientists have developed a drug that inhibits enzyme A.The drug is given to pancreatic cancer patients who have the gene mutation that stops cancer cells producing enzyme B. The drug only targets cancer cells.

  Explain why the drug can be used to treat pancreatic cancer in patients with the gene mutation.

  cancer cells cannot divide so tumour less likely to spread.because enzymes A and B are not working.
• A monoclonal antibody has been produced to treat pancreatic cancer. Explain how the monoclonal antibody works to treat pancreatic cancer.


  monoclonal antibody is attached to toxin.monoclonal antibody will

  attach to cancer cells so toxin will stop them dividing.
• Explain how the human lungs are adapted for efficient exchange of gases by diffusion.

  alveoli- provide a large surface area

  capillary walls- are one cell thick which provides short diffusion path (for oxygen / carbondioxide)

  large capillary network and good blood supply remove oxygen blood quickly bring carbon dioxide the lungs quickly and maintain a concentration.
• Nitrate ions need a different method of transport into the root hair cell. Explain how the nitrate ions in Figure 4 are transported into the root hair cell.

  active transport- energy is needed to move nitrate ions from a low concentration in the soil to a high concentration in the root.
• Explain the ‘lock and key theory’ of enzyme action.

  enzyme binds to the substrate because they are complementary so substrate is broken down so products are released
• Explain why the leaf left in a cupboard with no light for two days did contain glucose but did not contain starch.

  starch has been converted to glucose so can be used for respiration

  because there is no light to make glucose by photosynthesis
• A scientist noticed that in one area the gorse plants had yellow leaves and had stunted growth.

  One reason for yellow leaves and stunted growth is a deficiency of nitrate ions in the soil.

  Explain two other possible reasons for the yellow leaves and stunted growth.

  Do not refer to nitrate ions in your answer.

  • lack of magnesium so not enough chlorophyll for photosynthesis so not enough glucose to make proteins for growth.

  • infection by pathogen so leaves become discoloured
• Candida albicans lives in the throat of infected patients.A sample is taken from the throat of a patient with a suspected Candida albicans infection.The sample is transferred onto a microscope slide.

  Describe how the mAbs and a fluorescent dye could be used to see any Candida albicans pathogens on the slide.


  bind fluorescent dye to mAbs.put fluorescent mAbs on the slide .

  mAbs will bind to Candida pathogens and show up under the microscope.
• Describe how the clinical trials should be carried out.

  tested on cells to check efficacy.given to healthy volunteers at low dose

  to test for toxicity/side effects/efficiacy.

  then to some patients to test for the optimum dose and side effects and efficacy. double blind trial where neither patients nor doctors know who has the mAbs and who has a placebo.
• On day 10, the pond snail died.

  Explain why the death of the pond snail caused the concentration of carbon dioxide to increase after day 10.

  snail is being decayed by decomposers so respiration releases CO2
• Explain how amylase breaks down starch.

  Answer in terms of the ‘lock and key theory’.

  substrate binds to active site as shape of active site and substrate are complementary.a chemical reaction occurs to produce smaller molecules.
• Compare the structure and function of xylem tissue and phloem tissue.

  Structure-xylem is made of dead cells and phloem is made of living cells.phloem cells have pores in their end walls and xylem cells do not have pores in their end walls. xylem is hollow. xylem contains lignin

  and phloem does not.

  Function- xylem transports water / mineral ions

  and phloem transports sugars.xylem is involved in transpiration

  and phloem is involved in translocation.xylem is a one way flow and phloem is a 2 way flow.
• In one type of blood transfusion, only red blood cells from a donor are transferred to the patient.

  It is dangerous for a patient with blood group A to receive red blood cells from a donor with blood group B.

  Explain why.

  anti-B antibodies in patient will bind to type B antigens on person’s red blood cells so red blood cells clump together and block capillaries so cells have reduced supply of oxygen.
• Suggest how the monoclonal antibody for HIV helps to prevent a person infected with HIV developing AIDS.

  Use information from Figure 9.

  monoclonal antibody is complementary to HIV antigen.monoclonal antibodies attach to HIV antigens so HIV cannot bind to cell
• A person with late stage HIV infection has AIDS.

  Scientists have produced monoclonal antibodies for HIV.

  The monoclonal antibodies can prevent a person infected with HIV developing AIDS.

  Describe how the monoclonal antibody for HIV can be produced.

  HIV injected into mouse.extract lymphocytes that make a specific antibody to HIV.lymphocytes are combined with a tumour cell to create a hybridoma cell.hybridoma cloned to create many cells that produce the antibody
• The changes in the mean width of the stomata in normal conditions are an advantage to the plant.

  Explain how.

  stomata closed at night because there is no light for photosynthesis which prevents water loss.stomata open wide at midday

  as maximum light intensity for photosynthesis and to take in

  more carbon dioxide for photosynthesis
• The larvae of the hornet moth form when fertilised eggs divide by mitosis.

  Describe how mitosis produces two genetically identical cells.

  DNA replicated.the replicated chromosomes are pulled apart.cytoplasm divides into two.the set of chromosomes in each

  new cell are identical.